Crashes and startup problems of PHP may be encountered when loading the recode as extension after loading any extension of mysql or imap. Loading the recode before those extension has proved to fix the problem. This is due a technical problem that both the c-client library used by imap and recode have their own hash_lookup() function and both mysql and recode have their own hash_insert function.

The IMAP, recode, YAZ and Cyrus extensions cannot be used in conjuction, because they share the same internal symbols.